Every time I hit a box or rail I lean back pretty much as far as you can go without slipping, bend my back leg, keep my front leg mostly straight and have my back ski flat with my front one on its inside edge.
I think it might look cool (don't film), and I don't slip out, but its pretty much making it impossible to start to get switch ups/270's. No solid base. I always try to think about getting my weight as far forward as possible but my grinds almost always end up like that.